[refactor] Attachment images (#11961)

* Add new Attachment model fields:

- is_image
- thumbnail

* Cache if the attachment is an image

* Add new setting for controlling max upload size

* Validate uploaded attachment file

* Add tqdm for progress bars

* Refactor migrations

- Don't need is_image field
- Can introspect from the thumbnail

* Data migration for existing attachments

* Bump API version

* Update tests and validators

* Add "is_image" field to the Attachment model

* Offload to background task

* Implement unit tests

* Docs

* Add unit test for data migration

* Additional unit test

* Omit migration tests from code coverage

* Additional unit tests

docs/docs/concepts/attachments.md

@@ -25,6 +25,19 @@ The following types of attachments are supported:
 
 File attachments allow users to upload files directly to InvenTree. These files are stored on the server and can be downloaded or viewed by users with appropriate permissions.
 
+### Image Thumbnails
+
+When a file attachment is uploaded, InvenTree automatically determines whether the file is a valid image. If it is, a thumbnail is generated and stored alongside the attachment.
+
+- The thumbnail is created with a reduced image size, while preserving the original aspect ratio.
+- Thumbnail generation is performed in the background after upload.
+- The `is_image` flag on the attachment record is set to `True` for valid images, and `False` for all other file types.
+- If the uploaded file has an image extension but contains invalid or corrupt image data, no thumbnail is generated and `is_image` remains `False`.
+- Link attachments (external URLs) are never assigned a thumbnail.
+
+!!! info "Supported Formats"
+    Any image format recognised by the [Pillow](https://pillow.readthedocs.io/) library (e.g. PNG, JPEG, GIF, BMP, WEBP) will be treated as a valid image and have a thumbnail generated automatically.
+
 ### Link Attachments
 
 Link attachments allow users to associate external URLs with an object. This can be useful for linking to external documentation, resources, or other relevant web content.

docs/docs/settings/global.md

@@ -33,6 +33,7 @@ Configuration of basic server settings:
 {{ globalsetting("DISPLAY_FULL_NAMES") }}
 {{ globalsetting("DISPLAY_PROFILE_INFO") }}
 {{ globalsetting("WEEK_STARTS_ON") }}
+{{ globalsetting("INVENTREE_UPLOAD_MAX_SIZE") }}
 {{ globalsetting("INVENTREE_STRICT_URLS") }}
 
 Configuration of various scheduled tasks: